1. Field of the Invention
The present invention relates to an image sensing method and an image sensor utilizing the method, and particularly relates to an image sensing method and an image sensor utilizing the method that can adjust background light image brightness of the image sensor to be more uniform.
2. Description of the Prior Art
An image sensor is an apparatus that can transfer light to voltage charge, and processes the voltage charge to generate digital signals constituting the image. Such kind of digital signals can be stored to a storage apparatus or be output to a display to display an image corresponding to the digital signals. Such technology is applied to various kinds of electronic apparatuses, for example, a digital camera, a video camera, a mobile phone or a mouse.
The image sensor can be applied to touch control technology. FIG. 1 is a schematic diagram illustrating a prior art optical touch control apparatus 100. As shown in FIG. 1, the optical touch control apparatus 100 comprises an image sensor 102, bar shape light guiding devices 105, 109 and light emitting diodes 103, 107, 111, 113. The light guiding devices 105, 109 are provided at two sides of the sensing region 101. The light emitting diodes 103, 107, 111, 113 are located at the ends of the light guiding devices 105, 109, such that the light can be projected to the sensing region 101 via the light guiding devices 105, 109. Also, the image sensor 102 is provided opposite to the light guiding devices 105, 109.
FIG. 2 is a schematic diagram illustrating brightness distribution for the background light image derived by a prior art image sensor. As shown in FIG. 2, the brightness distribution of the background light image is non-uniform. One possible reason for such situation is that the intensities for the light emitted from the light guiding devices 105, 109 are different. Such situation may be caused by other reasons, however. Such informality may cause some problems. For example, if some objects such as a finger is put on the sensing region 101, the light is blocked such that a dark image is formed. For example, the dark image regions Ob1, Ob2, Ob3 and Ob4 in FIG. 2. Therefore, the optical touch control apparatus 100 utilizes the location of the dark image regions to compute the location and the barycentre of the object.
However, if the brightness distribution of the background light image is non-uniform, the location and the barycentre of the object may be wrongly determined. For example, the dark image regions Ob1, Ob2, Ob3 and Ob4 in FIG. 2 indicate the existence of object. The location and the barycentre of the object causing the dark image regions Ob1, Ob2 can be correctly computed since the brightness distribution of the background light image for the locations thereof are uniform. However, the location and the barycentre of the object causing the dark image regions Ob3, Ob4 may be wrongly computed since the brightness distribution of the background light image for the locations thereof are non-uniform.